The effect of hydrogen addition on the carbon-deposition behaviour during the reduction of pellets for the blast furnace process

Abstract

With the application of large amount of pulverised coal injection into the blast furnace, the hydrogen content in the gas will increase, which accelerates the reduction of iron ore in lump zone of the blast furnace as well as carbon-deposition reaction. This study has investigated the effect of hydrogen addition on carbon-deposition reaction during the reduction of pellets through thermodynamic calculation and experiment. The results show that H 2 can promote the carbon-deposition reaction, while the increase of temperature and CO 2 can significantly inhibit it. The preference region of temperature for C formation is about 600°C. Moreover, the promotion effect of H 2 on the carbon-deposition reaction at 700°C is better than that at 600°C. The SEM observation results show that the generated carbon is mainly distributed on the surface of the pellet, and only a little carbon is located inside the pellet. The agglomerated carbon could be more easily formed due to the dramatic carbon-deposition reaction caused by the lower temperature or higher H 2 content. But, most of the carbon just exists as an individual particle at the lower carbon-deposition reaction rate. The results of SEM-EDS reveal that carbon deposited is primarily in the form of elemental carbon rather than in the form of cementite. The study also shows that with increasing reduction time, the rate of carbon-deposition increases, mainly due to the promotion effect of reduced iron during the reduction process of pellets.

Characteristics and catalytic behavior of Ru–Sn bimetallic catalysts for TMCB hydrogenation to CBDO

“…16d that a small amount of non-existent flake substances are attached to the surface of the catalyst, which may be Ru oxide produced during the recycling of the catalyst. 37 …”

“…16d that a small amount of non-existent ake substances are attached to the surface of the catalyst, which may be Ru oxide produced during the recycling of the catalyst. 37 In order to further investigate the cause of catalyst deactivation, the recovered catalyst was analyzed by X-ray photoelectron spectroscopy. Fig.…”

Review of hydrogen-rich ironmaking technology in blast furnace

“…Active iron catalyses the carbon deposition reaction, With the gradual migration of reduced iron to the surface of pellets, the deposition of carbon on the surface of pellets is intensified, leading to a reduction of internal carbon deposition. As a result, the pellet expansion is reduced [113][114][115].…”

Study on sticking mechanism of pellets under low H2/CO conditions

“…The sticking behavior of iron ore during reduction can be interpreted as the connection of newly formed metallic iron on the ore surface and liquid phase formed by low melting point material (CaO-SiO2-FeO) [5,[9][10][11][12][13] . The sticking behavior of pellets, occurring in the metallization of pellets, was accompanied by the formation of fibrous metallic iron [14] .…”